With regards to the recent meta post on a user's ability to admit their question is a duplicate

As of the 9th of March, the banner shown to askers whose questions have attracted at least one duplicate close vote has a couple of new options: If the author clicks the first button, they're shown a confirmation that clarifies the results of this action somewhat:

If they click "Ok", the question is instantly closed:

Which is what I think happened to that question.

With regards to the recent meta post on a user's ability to admit their question is a duplicate

As of the 9th of March, the banner shown to askers whose questions have attracted at least one duplicate close vote has a couple of new options: If the author clicks the first button, they're shown a confirmation that clarifies the results of this action somewhat:

If they click "Ok", the question is instantly closed:

Which is what I think happened to that question.

With regards to the recent meta post on a user's ability to admit their question is a duplicate

As of the 9th of March, the banner shown to askers whose questions have attracted at least one duplicate close vote has a couple of new options: If the author clicks the first button, they're shown a confirmation that clarifies the results of this action somewhat:

If they click "Ok", the question is instantly closed:

Which is what I think happened to that question.

With regards to the recent meta post on a user's ability to admit their question is a duplicate

As of the 9th of March, the banner shown to askers whose questions have attracted at least one duplicate close vote has a couple of new options: If the author clicks the first button, they're shown a confirmation that clarifies the results of this action somewhat:

 
If they click "Ok", the question is instantly closed:

Which is what I think happened to that question.